EP2616741A1 - Solid-fuel-fired hot gas generator having an extended control range - Google Patents

Abstract

The invention relates to a solid-fuel-fired hot gas generator, which has a plurality of solid fuel burners (3, 4, 5) in order to extend the control range. Said solid fuel burners form a multiple solid fuel burner (10) having an extended control range. A solid fuel supply (6) and a combustion air supply (7) are associated with each solid fuel burner, and a separate, metered solid fuel supply to each solid fuel burner is guaranteed by means of a metering apparatus. The firing power of the multiple solid fuel burner, which in particular is a multiple impulse burner, ranges from the minimum power of one of the solid fuel burners to the maximum power of all solid fuel burners, so that the control of all required load ranges of a plant unit to be supplied is covered.

Description

 Solid-fired hot gas generator with extended control range

The invention relates to a solids-fired hot gas generator with an extended control range, which can preferably be used in grinding drying plants, for example for grinding solid fuels.

Coal grinding plants with an air-flow mill, for example a vertical roller mill of the LOESCHE type, a spherical roller mill or a roller ring mill, in which moist raw coal is subjected to grinding drying by supplying hot gas and ground into pulverized coal, with a separation unit, for example a filter, in where the pulverized coal gas mixture is separated and with a hot gas generator for producing the hot gas, to which a part of the gas is returned as a return gas, are from coal gasification, pig iron and steel production with PCI (Pulverized Coal Injection) processes and from the cement industry known (DE 40 35 730 C2, prospectus LOESCHE GmbH, Dusseldorf, "Loesche - mills for solid fuels", 01/2008).

Coal dust fired hot gas generators are also used in the stone and earth industry for drying raw meal, slag and blastfurnace slag and cement, and also in the gypsum, sugar and potash industries hot gas generators fired with lignite or hard coal dust are known.

A hot gas generator with a burner which is fired with pneumatically conveyed combustible dust, for example hard coal or lignite dust, biomass dust or mixtures thereof, with the supply of combustion air, a burner muffle arranged on the outlet side, a feed for the gas to be heated and a mixing part, which is arranged downstream of the burner muffle and designed as a perforated jacket (LOMA) with staggered cylinder sections and with a nem protective jacket forms an annular channel for the gas to be heated, is known from DE 197 06 077 A1.

A perforated jacket device made of metal for the inflow of the gas to be heated and a burner muffle, which is formed in the axial direction substantially shorter than the perforated shell device and lined with refractory material, already has the Heiligaserzeuger described in DE 42 08 951 A1. However, here the burner is a multi-lance burner with surrounding lean-gas combustion air nozzles.

DE 197 25 613 A1 describes a burner for producing hot exhaust gases by combustion of heating oil or heating gas or pulverized coal. The pulverized coal is transported with a gaseous carrier medium, preferably air, and blown into the reaction space through an injection lance, which extends from the burner head to the point of maximum diameter of a conical reaction space and is provided with a deflecting hood at the outlet end. The combustion air is supplied via a radial blade grid at the head end of the reaction space. The blade grid and part of the reaction space are surrounded by an air collecting housing in which the combustion air is to be calmed and from which the combustion air passes via the blade grid into the reaction space. As a result of its flow pattern, the burner generates a particularly large range of turbulent fluctuation movements. The fuel dust is transported back to the air guide vanes after exiting the deflector hood and heated by a swirling, helical flame to about 1000 ° C and ignited. The flame jet has a strong impulse and produces a very fast recirculation of the gases.

In the Internet publication "Impuls-Brenner, Dr.-Ing. Schoppe, for lignite dust, heating oil and gas from 100 kW to 35 MW ", the above burner is called impulse burner.

A development of the pulse burner, which should have an increased flame stability and flame jet velocity for a hot gas temperature range of at least 200 ° C to 900 ° C, is described in DE 102 32 373 B4. Burners for solid fuels, which are used in conjunction with mixing chambers, have a maximum control range of 1: 5. This technically justified limitation of the control range complicates or prevents the use of hot gas generators with mixing chambers, such as a perforated shell device, in process engineering plants, which require higher control ranges, for example, control ranges to 1:10. Such control ranges can be caused by strongly fluctuating moisture of the material to be dried and changes in the throughput of the unit to be supplied.

For example, the throughput of a vertical roller mill of the LOESCHE type is between 100% and 40%. The mill thus has a control ratio of 1: 2.5. When a minimum throughput coincides with a very low humidity and a relatively high outside temperature, only a relatively small amount of heat is required. Maximum heat consumption results from maximum throughput, maximum humidity of the material to be milled and dried and a relatively low outdoor temperature.

The following concrete example is intended to clarify that a control ratio of about 1: 8 is required in order to be able to approach all "operating points".

Example: hard coal

Max-Fall: Throughput = 80 t / h

 Humidity 15%

 Temperature 5 ° C

Amount of heat 49.66x10 ⁶ kJ / h (13.8 MW)

Min case: throughput 32 t / h

 Humidity 5%

 Temperature 35 ° C

Amount of heat 6.1x10 ⁶ kJ / h (1.695 MW)

The control ratio is thus: 49.66: 6.1 = 1: 8.14. The aforementioned control ratio of 1: 8,14 is so far achieved with any hot gas generator with a solid fuel burner. Therefore, unless waste heat from the process itself is available, hot gas generators with a gas or oil burner are predominantly used in grinding and drying plants for grinding coal. In coal gasification plants, the hot gas generator is usually fed with synthesis gas as fuel and blast furnace gas for combustion in PCI systems. Coal gasification plants for coal gasification, PCI plants and in the cement industry require control ranges of at least 1: 8. As a rule, a control ratio of at least 1:10 for oil and gas fired hot gas generators is already state of the art.

The invention has for its object to provide a solids-fired hot gas generator, in particular a coal dust-fired hot gas generator, with an extended control range to replace fuel oil and gas by a cost fuel, such as lignite dust, hard coal dust, etc., and also the economically inefficient use of Syngas, blast furnace gas etc. for the production of hot gases in hot gas generators can turn off.

According to the invention the object is achieved by the features of claim 1 and claim 2. Advantageous and advantageous embodiments are contained in the subclaims and the description of the figures.

A basic idea can be seen to equip a hot gas generator with multiple burners to increase the control range.

According to the invention, a solids-fired hot gas generator has a plurality of solid fuel burners for increasing or expanding the control range, so that a multiple solid fuel burner is formed.

Each solids burner is associated with an independent solids feed and combustion air supply, and each solid fuel burner can be fired independently of the other solid fuel burners. The firing capacity of the multi-purpose solid fuel burner then ranges from the minimum output of one of the solid fuel burners to the maximum output of all arranged solid fuel burners. The control range is thus extended, and all load ranges of an aggregate, to which the hot gas produced in the hot gas generator is supplied, can be covered. In a preferred embodiment, a hot gas generator with a burner muffle and a starting burner, which is arranged in a burner plate of the burner muffle, with a feed device for the gas to be heated and with a mixing part, in which the generated combustion gas is mixed with the gas to be heated and which of the burner muffle downstream, a plurality of solid fuel burner, which are arranged coaxially with the starting burner and fixed in the burner plate of the burner muffle.

The number of burners can advantageously be adapted to the respective requirements. For example, two, three or four, possibly even more solid fuel burner can be flanged to the burner plate of the burner muffle. Also advantageous equal or different sized burners can be used, that is, burners are arranged with equal or different sized firing capacity.

The hot gas generator according to the invention is advantageously carried out in a vertical design and the multiple solid fuel burner is designed and arranged in the burner plate of the burner muffle that the solid fuel burner with its coal dust feed and its reaction chamber into the burner muffle.

It is advantageous if three solid fuel burner are arranged at the same distance from one another and coaxially with the starting burner guided on a longitudinal axis of the burner muffle and through the burner plate. The burners can also be arranged at a defined angle, such that the flue gases emerging from the burners are guided to the center of the exit of the burner muffle. Since the solids burners are provided for ash-containing fuels, a vertically or obliquely downward leading arrangement is recommended in the burner plate or in the burner muffle of the hot gas generator.

It is furthermore advantageous that a burner muffle, which only has to be adapted in its dimensioning of the intended number of solid fuel burners in the burner plate, can be used. The burner muffle may be lined with a refractory material.

In addition, it is expedient if the burner muffle is surrounded by a feed device for the gas to be heated and the gas to be heated corresponds to the subsequent following mixing part for mixing with the generated combustion gas can be supplied.

Advantageously, as a mixing part, a perforated jacket device may be arranged, which is designed as a steel combustion chamber and in the axial direction has a plurality of cylindrical and coaxial perforated coats, which form at their transitions annular gaps for the inflow of gas to be heated, and are surrounded by an outer, closed steel jacket to form an annular channel , Such a steel sheet chamber is known as LOMA combustion chamber.

Pulp burners from Carbotechnik Energiesysteme GmbH, Geretsried, for example, which have already been described above in connection with DE 197 25 613 A1 and DE 102 32 373 B4 and an Internet publication of this company, can be used to advantage as solid burners. However, other solid fuel burners can be used.

The pulse burners have outputs between 0.5 and 100 MW and are suitable for arrangement in an upper, end-side burner plate of the burner muffle of the hot gas generator according to the invention, so that a multiple impulse burner is formed.

For a separate control and regulation of each solid fuel burner, a metering device is provided which can supply each solid fuel burner individually and independently of the operation of the adjacent burner with pulverized coal and can approach any desired control point.

Particularly suitable is the CT dosing machine for fluidizing, dosing and pneumatic conveying of Carbotechnik Energiesysteme GmbH, Geretsried.

The metering machine is described in an Internet publication of the aforementioned company and in EP 0 054 018 B1 and EP 0 210 162 B2.

The expanded or increased control range of the hot gas generator according to the invention with a multiple solid fuel burner or a multiple impulse burner will be explained below with reference to the example described in the introduction. In this example, a maximum amount of heat of 13.8 MW was required. For procedural reasons and in view of the integration of the burners in the burner muffle, a number of solid fuel burners is selected as the optimal arrangement. Each solid fuel burner then has to bring a power of 4.6 MW. With a control range of a single solid burner of 1: 4 results in a minimum power of 1, 15 MW. Thus, the required amount of heat of 1, 695 MW even falls below and the control range of a single solid burner of 1: 4 extended to a control range of the multi-burner invention with three solid fuel to 1:12.

Depending on the heat requirement, only one solid fuel burner of the multiple burner arrangement can be put into operation, or two or all three fuel burners can be put into operation. The total control ratio is then for the hot gas generator with three solid burners at 1:12.

Such a value can only be achieved in exceptional cases with gas burners.

The multiple solid fuel burner arrangement according to the invention on or in the burner muffle of a hot gas generator thus makes it possible to produce hot gases, grinding drying plants and other thermal plants in an extraordinarily efficient manner. Particularly advantageous is the use of solid fuels, such as lignite dust, which is much cheaper compared to fuel oil and fuel gases and is also present in sufficient quantity. When using blast furnace gas or synthesis gas for the production of hot gases for drying purposes, especially in coal grinding plants, a substitution with coal dust can be made.

The invention will be further explained below with reference to a description of the figures; In this show in a highly schematic representation:

Fig. 1 is an axial longitudinal section through an inventive

 Hot gas generator with a multiple solid fuel burner and

Fig. 2 is a plan view along line II-II in Fig. 1st

Figures 1 and 2 show a hot gas generator with a multi-solid fuel burner 10, which consists in this example of three solid fuel burners 3, 4, 5. From FIG. 1 with two solid fuel burners 3, 4 shown, it is clear that each solids burner 3, 4, 5 is assigned a solids feed 6 and a combustion air feed 7 and that the solid burners 3, 4, 5 are arranged in a burner plate 12 of a burner muffle 2. The burner muffle 2 and a downstream mixing part 9 are like the solid fuel burner 3, 4, 5 and a start burner 8 vertically aligned.

As a solid fuel burner 3, 4, 5 are pulse burners for coal dust, such as lignite dust, used which a conically widening reaction chamber 16 with a conically narrowing flame acceleration nozzle 17, an injection lance 18 with Umlenkhaube 19 for injecting fluidized coal dust and a radial Schaufeig itter 25 am Burner head through which combustion air enters the reaction chamber 16, which enters via a lateral inlet opening 7 in an air housing 28 and from here to the radial blade grid 25 and the reaction chamber 16 passes.

The solid fuel fired impulse burners have a high flame jet velocity and, as shown in FIG. 1, a flame 30 extends through the burner muffle 2 into the mixing part 9.

If no solid fuel is available, the pulse burners can be switched to gas to maintain operation of subsequent equipment. From Fig. 1 go in addition to the solid feeds 6 gas feeds 27 to the visible here solid or impulse burners 3, 4.

In the mixing part 9, the heating and mixing of the combustion gases generated in the multi-solid burner 0 takes place with heated process gas 13, which is supplied via a feed device 11.

The feed device 1 surrounds with its radial housing the burner muffle 2, in which the solid fuel burner 3, 4, 5 extend their reaction chamber 16 and the flame acceleration nozzle 17.

The burner muffle 2 is lined in this embodiment with a refractory material 15. The refractory lining may also be omitted. On the burner muffle 2, on the outlet side and thus opposite to the multiple solid burner assembly 10 in the burner plate 12, as a mixing part 9, a perforated jacket device closes. 20. This perforated jacket device 20 is part of the steel combustion chamber and consists of several cylindrical and coaxial perforated jackets 21 with increasing diameters. Between the individual perforated jackets 21 are annular gaps 22 for the inflow of the heated gas 13 and between the perforated jackets 21 and an outer closed steel jacket 23, an annular channel 24 is formed, in which the heated gas 13 from the feed device 11 and then through the annular gaps 22 and holes of Hole jacket 21 enters the mixing chamber 26. The formed hot gas 14 is discharged via an outlet opening 29.

Fig. 2 shows a plan view of the hot gas generator at the level of the burner plate 12 of the burner muffle 2 with the arranged on the circumference of the burner muffle 2 volute casing of the feed device 11 for the gas to be heated. A starting burner 8, which is operated with gas or oil, is arranged in the center of the burner plate 12 and the three solid fuel burners 3, 4, 5 extend coaxially and equidistant from each other and to the starting burner 8 vertically downwards.

The solid fuel burners 3, 4, 5 used as impulse burners are also suitable for the combustion of gases. If coal dust is not available in an accident, the pulse burners can be easily converted to natural gas, syngas or blast furnace gas, so that the operation of downstream equipment such as a coal gasification power plant, blast furnace at PCI plants, etc. can be maintained.

An essential advantage of the multiple solid fuel burner according to the invention is the expansion of the field of use of hot gas generators with solid fuel burners.

The use of a hot gas generator with multiple solid fuel burners, in particular multiple impulse burners, offers itself in coal gasification plants as well as in PCI plants in the steel industry and for multicolored metallurgical procedures as well as in general heat technical plants. As a result, the synthesis gas produced in the coal gasification can be used advantageously in the energy-producing industry and increasingly in the plastics industry. If, on the other hand, synthesis gas is branched off as energy carrier for the grinding drying, this requires at usual heat outputs between 10 and 30 MW synthesis gas quantities of 3300 m _N ³ / h to 10000 m _N ³ / h with a calorific value of the synthesis gas of about 11000 kJ / m _N ³ . This represents a considerable loss for the intended use. Blast furnace gas from the steel industry is also being used more and more frequently in special power plants to generate electricity. The use of coal dust for hot gas production avoids the use of the above-mentioned gases and other fuels, such as light and heavy oil, natural gas, etc. in hot gas generators and is extremely advantageous in energy and investment terms.

Claims

1. Solid-fired hot gas generator with an extended control range, characterized  that a plurality of solid fuel burners (3, 4, 5) are arranged and a multiple solid fuel burner (10) is formed,  that each solid fuel burner (3, 4, 5) is assigned an independent solids feed (6) and combustion air feed (7), and  the firing capacity of the multiple solid fuel burner (10) can be regulated from the minimum power of a solid fuel burner to the maximum power of all solid fuel burners (3, 4, 5) and covers all required load ranges of the subsequent turbine unit. 2. hot gas generator according to claim 1,  with a burner muffle (2) and a starting burner (8) which is arranged in a burner plate (12) of the burner muffle (2),  with a feed device (10) for gas (13) to be heated and with a mixing part (9) connected downstream of the burner muffle (2), in which the combustion gas produced is mixed with the gas (13) to be heated,  characterized, in that a plurality of solid fuel burners (3, 4, 5) are arranged coaxially with the starting burner (8) and fastened in the burner plate (12) of the burner muffle (2). 3. hot gas generator according to claim 1 or 2,  characterized,  that equal size or different sized solid fuel burner (3, 4, 5) form a multiple solid fuel burner (10). 4. hot gas generator according to claim 2 or 3,  characterized,  in that three solid fuel burners (3, 4, 5) are arranged at the same angular distance from one another and at the same radial distance from the start burner (8) in the burner plate (12). 5. hot gas generator according to one of the preceding claims,  characterized,  in that the solid fuel burners (3, 4, 5) are arranged at a defined angle to the longitudinal axis of the burner muffle (2). 6. hot gas generator according to any one of the preceding claims,  characterized,  a metering device is provided for a separate, metered solids feed to each solid fuel burner (3, 4, 5). 7. hot gas generator according to one of the preceding claims,  characterized,  that the solid fuel burners (3, 4, 5) pulverulent fuel, in particular pulverized coal or biomass dust, in fluidized form can be fed. 8. hot gas generator according to one of the preceding claims,  characterized, that as solid fuel burner (3, 4, 5) impulse burners, especially for hard coal dust, lignite dust, petroleum coke dust, biomass dust and dust mixtures are arranged, each having a conically widening reaction space (16), optionally with a conically narrowing flame acceleration nozzle (17), and an injection lance (18) with deflection hood (19) for the fluidized dust-like fuel and a radial blade grid (25) for supplying combustion air. 9. hot gas generator according to claim 8,  characterized,  in that the pulse burners used as solid burners (3, 4, 5) are convertible to gas and can be operated, for example, with natural gas, synthesis gas or blast furnace gas. 10. hot gas generator according to one of the preceding claims,  characterized,  that as a mixing part (9) has a perforated shell device (20) (LOMA) with a plurality of cylindrical and coaxial perforated shells (21), with annular gaps (22) between the perforated shells (21) and with an annular channel (24) between the perforated shells (21) and a outer, closed steel jacket (23) is arranged. 11. Hot gas generator according to one of the preceding claims,  marked by  the use in coal gasification plants, PCI plants in the steel industry and in colorful metallurgical processes, in the cement industry and in general heat engineering plants.